97 Spinal Arteriovenous Fistula

Pascal M. Jabbour and Erol Veznedaroglu

Clinical Presentation

A 77-year-old woman with a history of high blood pressure and diabetes presents to the emergency room for progressive weakness in her lower extremities.

The weakness has been ongoing for the last 8 months, associated with episodes of bladder incontinence the last 3 weeks.

She denies any lower back pain or radicular pain. There is no history of trauma.

Neurologic examination reveals weakness in her proximal lower extremities’ muscle groups graded at 3/5 with spasticity. Distally, her strength is graded 4/5 on the Medical Research Council scoring system. Sensation is intact. She has increased deep tendon reflexes and a right Babinsky. Her rectal tone is normal. She has normal strength in the upper extremities.

Magnetic resonance imaging (MRI) of the thoracic spine is shown in Fig. 97.1.

Fig. 97.1 T2-weighted magnetic resonance image (MRI), mid-sagittal section.

Fig. 97.2 Thoracic spine angiogram, anteroposterior view with selective injection of thoracic artery.

Questions

Where do you localize the lesion according to her examination?
Describe the MRI and angiogram findings.
What is the next imaging test to perform?
What are some clinical differences in spinal dural arteriovenous fistulas (DAVFs) and spinal intradural arteriovenous malformations (AVMs)?
What are the different treatment options for this patient?
What are some complications of management of spinal DAVFs?
What are the outcomes of treatment of spinal DAVFs?

Answers

Where do you localize the lesion according to her examination?

She has upper motor neuron signs with increased reflexes, Babinski, and spasticity. Her upper extremities are normal; therefore, the lesion is probably located at the level of her thoracic spine.

Describe the MRI and angiogram findings.

The MRI shows edema in the spinal cord, with prominent flow voids representing engorged vessels surrounding the spinal cord.
The angiogram demonstrates a DAVF, which is also a type I spinal AVM.

What is the next imaging test to perform?

A spinal computed tomography (CT) angiogram or a spinal formal angiogram should be performed. Spinal angiogram is shown in Fig. 97.2.
What are some clinical differences in spinal DAVFs and spinal intradural arteriovenous malformations?
- Spinal DAVFs occur predominantly in male patients, whereas intradural AVMs are more equally distributed in both genders.
- The age of occurrence in spinal DAVFs is older than in intradural AVMs (46 years versus 24 years).
- Onset of symptoms is more gradual in spinal DAVFs.
- The first symptom is more likely to be paresis in spinal DAVFs whereas in intradural AVMs it is more commonly related to subarachnoid hemorrhage.
- Exacerbation of symptoms by activity is more common in spinal DAVFs.
- The upper extremities are more commonly affected in intradural AVMs.¹
What are the different treatment options for this patient?
- The goals of treatment consist of interrupting the vein draining the AVF as it penetrates the inner dural layer.²
- Her options include
  - Open surgery with clipping of the fistula, which usually resides in the sleeve of a nerve root. Laminectomies one level above and one below are usually performed. The dura can be opened in the midline and retraced laterally. The site of the fistula is identified and correlated with imaging studies. The arterialized vein is then coagulated and a limited resection is performed.^2,3
  - Endovascular embolization of the fistula^4,5
What are some complications of management of spinal DAVFs?
- Acute neurologic deficit postsurgery or postembolization
  - This necessitates immediate imaging studies via MRI, administration of steroids, followed by possible reexploration.
- Hematoma
- Postoperative infection
- Residual malformation or fistula on postoperative angiography (may require reoperation)
  - It is recommended to perform an angiogram ~1 week after surgical treatment.²
What are the outcomes of treatment of spinal DAVFs?
- In general, safe and successful treatment is achievable.
- In most cases, there is improvement of neurologic function or treatment – it usually arrests the progression of the symptoms. These good results can be seen in ~80–90% of patients.^1,3
- Most patients can ambulate after treatment.
- Bladder symptoms are often improved.
- Outcome correlates very much with initial neurologic condition upon presentation: patients with less neurologic deficit on presentation will fare better.^1,3